EDIT: This entire post refers mostly to FE vs. FE, specifically FE6 and after (where the +4 speed = double convention is used.) The idea of AS vs. games without AS is to be ignored here since that's a totally different argument altogether.
But doesn't even that +4 threshhold need to be averaged by game as well?
What? Doubling occurs when you're 4 points above average. Tibarn is 40 speed to a 29 average; that's 11 points above average. Lyn is, randomly, 28 speed to a 21 average; that's 7 points above average. Therefor, FE7 21 Speed is equivalent to FE10 29 Speed. This isn't a hard concept. Its like how we do ANY speed averaging. CT's 11 Average speed or whatever is equivalent to FF6's 35~ average speed, why can't we apply the same logic to FEs?
Tibarn may be 11 points above average AS, but if more people in his game are doubling average, then shouldn't the other FE games' lower AS average be taken into account when you're figuring out their AS as -defense- against being doubled?
First off, the reason more people double average in FE10 is cause its cast is much bigger than your standard FE. Secondly, I have no clue what you're actually saying here. What's this "lower AS" thing matter? If a character is 4 points below their average AS, they are doubled.
Lyon has 0 FE8 speed, he gets doubled by damn near everything under the sun, even Nergal. If FE8's average speed was only 3, then yeah, that 0 wouldn't seem as bad as Nergal's 14 or whatever, but FE8's average is in the 20s, so Lyon's ludicrously slow.
Flipside, Ike of FE10 has like 31 speed, faster than anyone prior in the series numerically outside of FE9 Naesala. Thing is? FE10's average is 29...so he's only 2 points above average. Thereby, he doesn't really double anything.
Weird things like this are the reason that I've mostly just been viewing AS as 'Do they double? yes/no'. FE speed rules are pretty headachey and I'm almost to the point where I'm just going to start treating AS as standard speed and doubling happens CTB-style.
There's really nothing hard about this to understand. Games have different average speeds, as I noted above, FE AS is no different. You have to find a way to make them compatible; FE7 does not have the same stat scale as FE8 (though, the two are close, I'm aware), which isn't the same as FE9, and all of them look nothing like FE10 and its stat scale which is much higher. Given FE games don't give a shit about %, and its all about raw addition and subtraction, its easy to make an adjustment.
Just do the following formula to figure out whether FE characters double:
Character's Speed - Average Speed of their HOME game. The enemies game is totally irrelevant.
Do this with both characters, then compare the two characters. Note the above value CAN be negative; that just means how far below average you are.
So FE10 Tibarn would have a score of "+11." FE7 Lyn would have a score of "+7." Eirika without her legendary is "+8". Nergal is "-10" or something really fail like that. FE9 Ike is "+4" (for sake of argument, I'm rounding up) Roy would have like a score of "+2 AS."
So Tibarn doubles everything in that list but Eirika.
Eirika doubles Ike, Roy and Nergal, but not Lyn, avoids getting doubled by Tibarn.
Lyn gets doubled by Tibarn, avoids getting doubled by Eirika, fails to double Ike, doubles Roy and Nergal no problem.
Ike doubles Nergal only, avoids being doubled by Lyn, gets doubled by Tibarn and Eirika.
Roy doubles no one but Nergal, and avoids getting doubled by no one but Ike.
Nergal sucks and is doubled by everyone!
Do you understand? Its a simple case of converting AS from their raw values into a +/- value relative to their respective averages. Just going "Do they double y/n?" isn't fair. Why should Florina double Fiora, when in game, when she faces an enemy of equivalent AS, she would fail miserably? Its giving an unfair advantage to fast FE characters and slow ones to go "Do they double y/n?"
As we can see in the above list, while Ike and Eirika would both double average, if the two square off, Eirika should be doubling Ike under cause she's still got +4 Speed on him despite Ike's already impressive value.